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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - arch/ppc64/kernel/kprobes.c
2 * Kernel Probes (KProbes)
3 * arch/ppc64/kernel/kprobes.c
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * Copyright (C) IBM Corporation, 2002, 2004
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation ( includes contributions from
24 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
25 * interface to access function arguments.
26 * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
30 #include <linux/config.h>
31 #include <linux/kprobes.h>
32 #include <linux/ptrace.h>
33 #include <linux/spinlock.h>
34 #include <linux/preempt.h>
35 #include <asm/cacheflush.h>
36 #include <asm/kdebug.h>
37 #include <asm/sstep.h>
39 static DECLARE_MUTEX(kprobe_mutex
);
40 DEFINE_PER_CPU(struct kprobe
*, current_kprobe
) = NULL
;
41 DEFINE_PER_CPU(struct kprobe_ctlblk
, kprobe_ctlblk
);
43 int __kprobes
arch_prepare_kprobe(struct kprobe
*p
)
46 kprobe_opcode_t insn
= *p
->addr
;
48 if ((unsigned long)p
->addr
& 0x03) {
49 printk("Attempt to register kprobe at an unaligned address\n");
51 } else if (IS_MTMSRD(insn
) || IS_RFID(insn
)) {
52 printk("Cannot register a kprobe on rfid or mtmsrd\n");
56 /* insn must be on a special executable page on ppc64 */
59 p
->ainsn
.insn
= get_insn_slot();
67 void __kprobes
arch_copy_kprobe(struct kprobe
*p
)
69 memcpy(p
->ainsn
.insn
, p
->addr
, MAX_INSN_SIZE
* sizeof(kprobe_opcode_t
));
73 void __kprobes
arch_arm_kprobe(struct kprobe
*p
)
75 *p
->addr
= BREAKPOINT_INSTRUCTION
;
76 flush_icache_range((unsigned long) p
->addr
,
77 (unsigned long) p
->addr
+ sizeof(kprobe_opcode_t
));
80 void __kprobes
arch_disarm_kprobe(struct kprobe
*p
)
83 flush_icache_range((unsigned long) p
->addr
,
84 (unsigned long) p
->addr
+ sizeof(kprobe_opcode_t
));
87 void __kprobes
arch_remove_kprobe(struct kprobe
*p
)
90 free_insn_slot(p
->ainsn
.insn
);
94 static inline void prepare_singlestep(struct kprobe
*p
, struct pt_regs
*regs
)
96 kprobe_opcode_t insn
= *p
->ainsn
.insn
;
100 /* single step inline if it is a trap variant */
102 regs
->nip
= (unsigned long)p
->addr
;
104 regs
->nip
= (unsigned long)p
->ainsn
.insn
;
107 static inline void save_previous_kprobe(struct kprobe_ctlblk
*kcb
)
109 kcb
->prev_kprobe
.kp
= kprobe_running();
110 kcb
->prev_kprobe
.status
= kcb
->kprobe_status
;
111 kcb
->prev_kprobe
.saved_msr
= kcb
->kprobe_saved_msr
;
114 static inline void restore_previous_kprobe(struct kprobe_ctlblk
*kcb
)
116 __get_cpu_var(current_kprobe
) = kcb
->prev_kprobe
.kp
;
117 kcb
->kprobe_status
= kcb
->prev_kprobe
.status
;
118 kcb
->kprobe_saved_msr
= kcb
->prev_kprobe
.saved_msr
;
121 static inline void set_current_kprobe(struct kprobe
*p
, struct pt_regs
*regs
,
122 struct kprobe_ctlblk
*kcb
)
124 __get_cpu_var(current_kprobe
) = p
;
125 kcb
->kprobe_saved_msr
= regs
->msr
;
128 void __kprobes
arch_prepare_kretprobe(struct kretprobe
*rp
,
129 struct pt_regs
*regs
)
131 struct kretprobe_instance
*ri
;
133 if ((ri
= get_free_rp_inst(rp
)) != NULL
) {
136 ri
->ret_addr
= (kprobe_opcode_t
*)regs
->link
;
138 /* Replace the return addr with trampoline addr */
139 regs
->link
= (unsigned long)kretprobe_trampoline
;
146 static inline int kprobe_handler(struct pt_regs
*regs
)
150 unsigned int *addr
= (unsigned int *)regs
->nip
;
151 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
153 /* Check we're not actually recursing */
154 if (kprobe_running()) {
155 /* We *are* holding lock here, so this is safe.
156 Disarm the probe we just hit, and ignore it. */
157 p
= get_kprobe(addr
);
159 kprobe_opcode_t insn
= *p
->ainsn
.insn
;
160 if (kcb
->kprobe_status
== KPROBE_HIT_SS
&&
162 regs
->msr
&= ~MSR_SE
;
163 regs
->msr
|= kcb
->kprobe_saved_msr
;
167 /* We have reentered the kprobe_handler(), since
168 * another probe was hit while within the handler.
169 * We here save the original kprobes variables and
170 * just single step on the instruction of the new probe
171 * without calling any user handlers.
173 save_previous_kprobe(kcb
);
174 set_current_kprobe(p
, regs
, kcb
);
175 kcb
->kprobe_saved_msr
= regs
->msr
;
177 prepare_singlestep(p
, regs
);
178 kcb
->kprobe_status
= KPROBE_REENTER
;
181 p
= __get_cpu_var(current_kprobe
);
182 if (p
->break_handler
&& p
->break_handler(p
, regs
)) {
186 /* If it's not ours, can't be delete race, (we hold lock). */
191 p
= get_kprobe(addr
);
194 if (*addr
!= BREAKPOINT_INSTRUCTION
) {
196 * PowerPC has multiple variants of the "trap"
197 * instruction. If the current instruction is a
198 * trap variant, it could belong to someone else
200 kprobe_opcode_t cur_insn
= *addr
;
201 if (is_trap(cur_insn
))
204 * The breakpoint instruction was removed right
205 * after we hit it. Another cpu has removed
206 * either a probepoint or a debugger breakpoint
207 * at this address. In either case, no further
208 * handling of this interrupt is appropriate.
212 /* Not one of ours: let kernel handle it */
217 * This preempt_disable() matches the preempt_enable_no_resched()
218 * in post_kprobe_handler().
221 kcb
->kprobe_status
= KPROBE_HIT_ACTIVE
;
222 set_current_kprobe(p
, regs
, kcb
);
223 if (p
->pre_handler
&& p
->pre_handler(p
, regs
))
224 /* handler has already set things up, so skip ss setup */
228 prepare_singlestep(p
, regs
);
229 kcb
->kprobe_status
= KPROBE_HIT_SS
;
237 * Function return probe trampoline:
238 * - init_kprobes() establishes a probepoint here
239 * - When the probed function returns, this probe
240 * causes the handlers to fire
242 void kretprobe_trampoline_holder(void)
244 asm volatile(".global kretprobe_trampoline\n"
245 "kretprobe_trampoline:\n"
250 * Called when the probe at kretprobe trampoline is hit
252 int __kprobes
trampoline_probe_handler(struct kprobe
*p
, struct pt_regs
*regs
)
254 struct kretprobe_instance
*ri
= NULL
;
255 struct hlist_head
*head
;
256 struct hlist_node
*node
, *tmp
;
257 unsigned long orig_ret_address
= 0;
258 unsigned long trampoline_address
=(unsigned long)&kretprobe_trampoline
;
260 head
= kretprobe_inst_table_head(current
);
263 * It is possible to have multiple instances associated with a given
264 * task either because an multiple functions in the call path
265 * have a return probe installed on them, and/or more then one return
266 * return probe was registered for a target function.
268 * We can handle this because:
269 * - instances are always inserted at the head of the list
270 * - when multiple return probes are registered for the same
271 * function, the first instance's ret_addr will point to the
272 * real return address, and all the rest will point to
273 * kretprobe_trampoline
275 hlist_for_each_entry_safe(ri
, node
, tmp
, head
, hlist
) {
276 if (ri
->task
!= current
)
277 /* another task is sharing our hash bucket */
280 if (ri
->rp
&& ri
->rp
->handler
)
281 ri
->rp
->handler(ri
, regs
);
283 orig_ret_address
= (unsigned long)ri
->ret_addr
;
286 if (orig_ret_address
!= trampoline_address
)
288 * This is the real return address. Any other
289 * instances associated with this task are for
290 * other calls deeper on the call stack
295 BUG_ON(!orig_ret_address
|| (orig_ret_address
== trampoline_address
));
296 regs
->nip
= orig_ret_address
;
298 reset_current_kprobe();
300 preempt_enable_no_resched();
303 * By returning a non-zero value, we are telling
304 * kprobe_handler() that we have handled unlocking
305 * and re-enabling preemption.
311 * Called after single-stepping. p->addr is the address of the
312 * instruction whose first byte has been replaced by the "breakpoint"
313 * instruction. To avoid the SMP problems that can occur when we
314 * temporarily put back the original opcode to single-step, we
315 * single-stepped a copy of the instruction. The address of this
316 * copy is p->ainsn.insn.
318 static void __kprobes
resume_execution(struct kprobe
*p
, struct pt_regs
*regs
)
321 unsigned int insn
= *p
->ainsn
.insn
;
323 regs
->nip
= (unsigned long)p
->addr
;
324 ret
= emulate_step(regs
, insn
);
326 regs
->nip
= (unsigned long)p
->addr
+ 4;
329 static inline int post_kprobe_handler(struct pt_regs
*regs
)
331 struct kprobe
*cur
= kprobe_running();
332 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
337 if ((kcb
->kprobe_status
!= KPROBE_REENTER
) && cur
->post_handler
) {
338 kcb
->kprobe_status
= KPROBE_HIT_SSDONE
;
339 cur
->post_handler(cur
, regs
, 0);
342 resume_execution(cur
, regs
);
343 regs
->msr
|= kcb
->kprobe_saved_msr
;
345 /*Restore back the original saved kprobes variables and continue. */
346 if (kcb
->kprobe_status
== KPROBE_REENTER
) {
347 restore_previous_kprobe(kcb
);
350 reset_current_kprobe();
353 preempt_enable_no_resched();
356 * if somebody else is singlestepping across a probe point, msr
357 * will have SE set, in which case, continue the remaining processing
358 * of do_debug, as if this is not a probe hit.
360 if (regs
->msr
& MSR_SE
)
366 /* Interrupts disabled, kprobe_lock held. */
367 static inline int kprobe_fault_handler(struct pt_regs
*regs
, int trapnr
)
369 struct kprobe
*cur
= kprobe_running();
370 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
372 if (cur
->fault_handler
&& cur
->fault_handler(cur
, regs
, trapnr
))
375 if (kcb
->kprobe_status
& KPROBE_HIT_SS
) {
376 resume_execution(cur
, regs
);
377 regs
->msr
&= ~MSR_SE
;
378 regs
->msr
|= kcb
->kprobe_saved_msr
;
380 reset_current_kprobe();
382 preempt_enable_no_resched();
388 * Wrapper routine to for handling exceptions.
390 int __kprobes
kprobe_exceptions_notify(struct notifier_block
*self
,
391 unsigned long val
, void *data
)
393 struct die_args
*args
= (struct die_args
*)data
;
394 int ret
= NOTIFY_DONE
;
397 * Interrupts are not disabled here. We need to disable
398 * preemption, because kprobe_running() uses smp_processor_id().
403 if (kprobe_handler(args
->regs
))
407 if (post_kprobe_handler(args
->regs
))
411 if (kprobe_running() &&
412 kprobe_fault_handler(args
->regs
, args
->trapnr
))
418 preempt_enable_no_resched();
422 int __kprobes
setjmp_pre_handler(struct kprobe
*p
, struct pt_regs
*regs
)
424 struct jprobe
*jp
= container_of(p
, struct jprobe
, kp
);
425 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
427 memcpy(&kcb
->jprobe_saved_regs
, regs
, sizeof(struct pt_regs
));
429 /* setup return addr to the jprobe handler routine */
430 regs
->nip
= (unsigned long)(((func_descr_t
*)jp
->entry
)->entry
);
431 regs
->gpr
[2] = (unsigned long)(((func_descr_t
*)jp
->entry
)->toc
);
436 void __kprobes
jprobe_return(void)
438 asm volatile("trap" ::: "memory");
441 void __kprobes
jprobe_return_end(void)
445 int __kprobes
longjmp_break_handler(struct kprobe
*p
, struct pt_regs
*regs
)
447 struct kprobe_ctlblk
*kcb
= get_kprobe_ctlblk();
450 * FIXME - we should ideally be validating that we got here 'cos
451 * of the "trap" in jprobe_return() above, before restoring the
454 memcpy(regs
, &kcb
->jprobe_saved_regs
, sizeof(struct pt_regs
));
458 static struct kprobe trampoline_p
= {
459 .addr
= (kprobe_opcode_t
*) &kretprobe_trampoline
,
460 .pre_handler
= trampoline_probe_handler
463 int __init
arch_init_kprobes(void)
465 return register_kprobe(&trampoline_p
);